Raisins: well studied, and the results stay modest

The strongest evidence on this page never tests raisins on their own. Across 17 randomised trials with 668 people, grape products carrying polyphenols lowered C-reactive protein by a standardised mean difference of 0.23 (95 percent CI 0.05 to 0.41, P = 0.013). That effect sat at doses above 500 mg a day and in trials running 12 weeks or more. Those trials pooled grape seed extract, grape extract, juice and raisins together, and C-reactive protein is a marker of inflammation that nobody feels move. A second synthesis, of 118 randomised trials of foods sold for endurance, found no significant effect for raisins. Grape, beetroot, cherry and pomegranate did show effects there, and the authors describe even those as trivial. Against a sports product, raisins held their ground. Ten endurance-trained men aged 18 to 33 rode two hours and then a 10 km time trial, finishing in 17.3 minutes on sun-dried raisins and 17.3 minutes on isocaloric jelly beans, with no difference in blood glucose. Ten men in one protocol shows raisins were not worse, which is weaker than a proof of equivalence. As a carbohydrate food they test low in two groups and moderate in a third: a glycaemic index of 49.4 in sedentary adults, 49.6 in prediabetic adults and 62.3 in trained adults, three groups of about ten people with no significant difference between them.

The numbers, per 100 g

How much is actually in it

• Raisins belong to the small group of foods that together supplied 15.5% of raffinose and 8.3% of stachyose intake in an Italian sample, prebiotic sugars that food tables almost never list. — 35 foods analysed by high-performance anion-exchange chromatography; intake estimated in 100 healthy controls from an Italian case-control study run between 2017 and 2019 (n = 35 foods, 100 people) Evidence C source
  Mean daily intake 0.236 g total fructo-oligosaccharides and 0.371 g total galacto-oligosaccharides; the group including raisins accounted for 3.9% of kestose, 1.2% of nystose, 15.5% of raffinose and 8.3% of stachyose

What your body absorbs

• The glycaemic index of raisins measured 49.4 in sedentary adults, 49.6 in prediabetic adults and 62.3 in trained adults, with no significant difference between the three groups. — 10 healthy sedentary adults, 11 aerobically trained adults and 10 prediabetic adults, each given 50 g of available carbohydrate from raisins and from a glucose reference on separate occasions (n = 31) Evidence C source
  Glycaemic index 49.4 (SE 7.4) sedentary, 49.6 (SE 4.8) prediabetic, 62.3 (SE 10.5) trained, P = 0.437 between groups; insulin index 47.3, 54.4 and 51.9 respectively

What it does to your health

• Across 17 randomised trials with 668 people, grape products carrying polyphenols lowered C-reactive protein by a standardised mean difference of 0.23. — 17 eligible randomised controlled trials, 668 participants in total, searched to 30 March 2020, registration CRD42018110169 (n = 668) Evidence A source
  Standardised mean difference -0.229 (95% CI -0.41 to -0.05), P = 0.013; effects concentrated at doses above 500 mg/day and interventions of 12 weeks or longer
• Across 18 prospective cohorts with 451291 people and 145492 new cases of hypertension, raisins or grapes fell on the lower-risk side, and the authors call the fruit subtype results mixed. — 18 prospective cohort studies, 451291 participants, 145492 hypertension cases, follow-up 3 to 28 years, ages 18 to 95, searched to 15 May 2022 (n = 451291) Evidence C source
  Summary relative risk per 200 g/day 0.97 (95% CI 0.95 to 0.99) for fruit and vegetables and 0.93 (0.89 to 0.98) for fruit; each fruit subtype association rests on 2 to 5 studies

Safety, limits and interactions

• In 20 children aged 7 to 11, raisins alone never pulled dental plaque below pH 6 over half an hour, while the commercial raisin bran cereal dropped it further than the raisins did. — 20 children aged 7 to 11, randomised controlled crossover, plaque pH measured with a touch microelectrode before and at 2, 5, 10, 15, 20 and 30 minutes after raisins, bran flakes, commercial raisin bran or an experimental raisin bran, against 10% sucrose and sorbitol controls (n = 20) Evidence B source
  Commercial raisin bran produced a larger pH drop than raisins at 10 minutes (P < .001); adding raisins to bran flakes blunted the drop beyond 10 minutes (P < .001); raisins alone stayed above pH 6 throughout
• Salmonella enterica turned up in 29% of 70 raisin samples sold loose from bulk bins in markets in Queretaro, Mexico. — 70 samples each of peanuts, pecans, raisins, sun-dried tomatoes and chocolate sprinkles bought in bulk from retail establishments in Queretaro, Mexico; 60 isolates characterised (n = 70 raisin samples) Evidence C source
  Raisins 29% positive, chocolate sprinkles 26%, peanuts 31%, pecans 40%, sun-dried tomatoes 52%; 68.3% of isolates resistant to at least one of 14 antibiotics; commonest serotype Tennessee, 51 of 60

What people believe that the data does not support

• Pooling 118 randomised trials of nitrate and polyphenol foods, raisins showed no significant effect on endurance performance while grape, beetroot, cherry and pomegranate did. — 118 randomised controlled trials in the meta-analysis, 59 on polyphenols, 56 on nitrate and three on L-citrulline, 40 different food sources (n = 118 trials) Evidence A source
  No significant effect for raisins; overall polyphenol effect SMD 0.17 and nitrate 0.15, both P<0.001 and both described by the authors as trivial
• In 10 trained cyclists, sun-dried raisins matched commercial sports jelly beans for 10 km time-trial performance and for blood glucose after two hours of riding. — 10 healthy endurance-trained male cyclists and triathletes aged 18 to 33, crossover, 120 minutes of constant-intensity glycogen depletion then a 10 km time trial, isocaloric raisins or jelly beans every 20 minutes (n = 10) Evidence B source
  Time trial 17.3 (SE 0.4) vs 17.3 (SE 0.4); power 229.3 (SE 13.0) vs 232.0 (SE 13.6) W; no difference in blood glucose, perceived exertion or flow; sensory acceptance higher for raisins, 50.7 vs 44.3

Who this works differently for

• Over 12 weeks, 51 people with type 2 diabetes who snacked on dark raisins instead of processed snacks had 23% lower post-meal glucose and systolic pressure 8.7 mmHg lower. — 51 participants with type 2 diabetes mellitus, 12-week randomised study of routine dark raisin consumption against alternative processed snacks (n = 51) Evidence B source
  Postprandial glucose -23% (P = 0.024); systolic blood pressure -8.7 mmHg, a 7.5% fall (P = 0.035); fasting glucose -19% and HbA1c -0.12%, neither significant; no change in weight, BMI, waist, insulin or any lipid
• Swapping snacks for 36 g of currants a day for 24 weeks lowered fasting glucose and interleukin-6 in patients with fatty liver, of whom 50 of 55 finished the trial. — 55 patients with non-alcoholic fatty liver disease and non-significant fibrosis, randomised for 24 weeks to nutritional counselling alone (27) or counselling plus two fruit servings of currants at 36 g/day replacing snacks of similar calories (28) (n = 55 enrolled, 50 completed) Evidence B source
  Fasting glucose and IL-6 fell significantly only in the currant arm; total body fat, waist circumference and trunk fat reduced in the currant arm; body weight, BMI, HbA1c and CRP fell in both arms with no difference between them
• When 26 children aged 8 to 11 ate an after-school snack until comfortably full, raisins left their intake across the whole day lower, and cookies raised it. — 26 normal-weight children aged 8 to 11 (11 boys, 15 girls), four separate weekdays a week apart, standardised breakfast, morning snack and lunch, then one of four ad libitum after-school snacks (n = 26) Evidence B source
  Lowest calories eaten from raisins and grapes, highest from cookies (P < 0.001); weight of raisins eaten about 75 g, similar to potato chips; cumulative daily intake lower after raisins and grapes and higher after cookies (P < 0.001)

What is still unknown

• Ninety grams of raisins a day for four weeks moved none of the inflammation, oxidative stress or arterial function markers in 36 healthy smokers. — 36 apparently healthy smokers eating under five servings of fruit and vegetables a day, open-label randomised controlled 4-week intervention, raisins equal to five fruit servings at 90 g/day (n = 36) Evidence B source
  No change in C-reactive protein, leptin, malondialdehyde, advanced oxidation protein products, flow-mediated dilatation, pulse wave velocity, ICAM-1 or nitric oxide between baseline and week 4 in either arm

The bottom line

What the trials support is a swap, raisins in place of the snack you would otherwise reach for. Fifty-one people with type 2 diabetes ate dark raisins instead of processed snacks for 12 weeks, and post-meal glucose came out 23 percent lower (P = 0.024) and systolic pressure 8.7 mmHg lower (P = 0.035). HbA1c, the measure of longer term control, moved 0.12 percent and did not reach significance, and the comparator was crisps and biscuits rather than nothing. In 55 patients with fatty liver, 28 of them swapped snacks for 36 g a day of currants for 24 weeks, and fasting glucose and interleukin-6 fell only in that arm, with 50 of the 55 finishing. Currants are dried Corinth grapes, a close relative of the raisin and a different product. Left to snack freely after school, 26 normal-weight children aged 8 to 11 ate about 75 g of raisins, the same weight as the potato chips on offer. Their calories across the whole day still came out lower than on the afternoon they were given cookies, over four afternoons that measured eating and nothing about weight. Teeth are one caution with real data behind it. In 20 children aged 7 to 11, raisins alone never took plaque pH below 6 across half an hour, while the commercial raisin bran cereal took it lower than the raisins themselves did. Plaque pH over 30 minutes is a proxy for caries risk and not a count of cavities. Dried fruit sold loose raises a second question. Salmonella enterica was found in 29 percent of 70 raisin samples taken from bulk bins in shops in Queretaro, Mexico, alongside 40 percent of pecans and 52 percent of sun-dried tomatoes. Dried fruit is dry enough that the bacterium survives without growing, and one Mexican city with open bins says nothing about packaged raisins elsewhere. We found no trial of raisins with any medicine, and none on kidney stones. Two results are worth carrying home as limits. Ninety grams of raisins a day for four weeks left C-reactive protein, malondialdehyde, flow-mediated dilatation and pulse wave velocity unchanged in 36 healthy smokers, in an open label trial. In 18 prospective cohorts covering 451291 adults and 145492 new cases of hypertension, raisins or grapes fell on the lower-risk side, and each fruit subtype in that analysis rests on two to five studies. The summary figures there, 0.93 per 200 g a day, describe fruit as a whole. Even the composition is thin: raisins were one of seven foods that together supplied 15.5 percent of the raffinose eaten by 100 Italian adults, prebiotic sugars that no food table lists, and that share cannot be split between the seven.

Sources

1. rais-r4-12 · food analysis and intake estimation
   Wheat bran, raspberries, chestnuts, walnuts, raisins, soy milk, and soy yoghurt overall accounted for 3.9% of kestose, 1.2% of nystose, 0% of 1F-β-fructofuranosylnystose, 15.5% of raffinose, and 8.3% of stachyose total intakes.
   Nutrients, 2025 · checked 2026-09-24
2. rais-r4-08 · clinical trial, glycaemic index measurement
   The GI of raisins was low (GI, < or = 55) in the S (49.4 +/- 7.4) and P (49.6 +/- 4.8) groups and was moderate (GI, 55-69) in the A group (62.3 +/- 10.5), but there were no differences among the subject groups (P = .437).
   Nutr Res, 2008 · checked 2026-09-24
3. rais-r4-01 · meta-analysis of RCTs
   Based on the results, grape products containing polyphenols decreased CRP levels significantly (SMD = −0·229; 95 % CI −0·41, −0·05; P = 0·013).
   Br J Nutr, 2021 · checked 2026-09-24
4. rais-r4-11 · meta-analysis of prospective studies
   Inverse associations were observed for apples or pears, blueberries, raisins or grapes, avocado, broccoli, carrots and lettuce, while positive associations were observed for cantaloupe, Brussels sprouts, cruciferous vegetables, and total and fried potatoes (n = 2-5).
   Eur J Nutr, 2023 · checked 2026-09-24
5. rais-r4-09 · randomised controlled trial
   Consumption of raisins or eRB did not reduce plaque pH below 6 over the 30-minute testing period.
   Pediatr Dent, 2009 · checked 2026-09-24
6. rais-r4-10 · prevalence survey
   The prevalence of S. enterica in chocolate sprinkles, raisins, peanuts, pecans, and sun-dried tomatoes was 26, 29, 31, 40, and 52%, respectively.
   J Food Prot, 2022 · checked 2026-09-24
7. rais-r4-02 · meta-analysis of RCTs
   For polyphenol-rich foods, benefits were found for grape, (nitrate-depleted) beetroot, French maritime pine, Montmorency cherry and pomegranate, while no significant effects were evident for New Zealand blackcurrant, cocoa, ginseng, green tea or raisins.
   J Int Soc Sports Nutr, 2021 · checked 2026-09-24
8. rais-r4-07 · randomised controlled trial
   Consuming SDRs or SJBs during 120 minutes of intense cycling results in similar subsequent TT performances and are equally effective in maintaining blood glucose levels during exercise.
   J Strength Cond Res, 2011 · checked 2026-09-24
9. rais-r4-03 · randomised controlled trial
   In this study, compared to alternative processed snacks, those who consumed raisins had a significant 23% reduction in postprandial glucose levels (P = 0.024).
   Phys Sportsmed, 2015 · checked 2026-09-24
10. rais-r4-05 · randomised controlled trial
    Significant differences between the two arms post-intervention were observed in fasting glucose and in IL-6 levels, these being significantly decreased only in Currant patients.
    Food Funct, 2016 · checked 2026-09-24
11. rais-r4-06 · randomised controlled trial
    Raisins and grapes led to lower cumulative food intake (breakfast + morning snack + lunch + after-school snack) (P < 0.001), while the cookies increased cumulative food intake (P < 0.001) compared to the other snacks.
    J Food Sci, 2013 · checked 2026-09-24
12. rais-r4-04 · randomised controlled trial
    No effect of daily raisin consumption was observed on markers assessed between baseline and week 4 in either arm.
    Food Res Int, 2017 · checked 2026-09-24